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hello-algo/zh-hant/codes/cpp/chapter_tree/binary_tree_bfs.cpp

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/**
* File: binary_tree_bfs.cpp
* Created Time: 2022-11-25
* Author: krahets (krahets@163.com)
*/
#include "../utils/common.hpp"
/* 層序走訪 */
vector<int> levelOrder(TreeNode *root) {
// 初始化佇列,加入根節點
queue<TreeNode *> queue;
queue.push(root);
// 初始化一個串列,用於儲存走訪序列
vector<int> vec;
while (!queue.empty()) {
TreeNode *node = queue.front();
queue.pop(); // 隊列出隊
vec.push_back(node->val); // 儲存節點值
if (node->left != nullptr)
queue.push(node->left); // 左子節點入列
if (node->right != nullptr)
queue.push(node->right); // 右子節點入列
}
return vec;
}
/* Driver Code */
int main() {
/* 初始化二元樹 */
// 這裡藉助了一個從陣列直接生成二元樹的函式
TreeNode *root = vectorToTree(vector<int>{1, 2, 3, 4, 5, 6, 7});
cout << endl << "初始化二元樹\n" << endl;
printTree(root);
/* 層序走訪 */
vector<int> vec = levelOrder(root);
cout << endl << "層序走訪的節點列印序列 = ";
printVector(vec);
return 0;
}